The Wellcome Trust Centre for the History of Medicine at UCL produces a wide range of publications, including the Wellcome Witnesses to Twentieth Century Medicine series. These volumes are edited transcripts of Witness Seminars at which significant figures in twentieth-century medicine discuss discoveries and events in recent medical history. Twenty-two published volumes are available from December 2004. For further details see: www ucl.ac.uk/histmed/witnesses.html The prevention of rhesus disease of the newborn stands as a stunning medical success story. This disease afflicted thousands of newborns each year, causing serious health problems, even death. Yet from the early 1940s to the 1970s British and American researchers uncovered the basis of the disease and developed the medical intervention that could prevent its occurrence. Many of the key steps leading to this remarkable achievement took place at the University of Liverpool School of Medicine. Chaired by Professor Sir David Weatherall this Witness Seminar, 'The Rhesus factor and disease prevention' (volume 22), examines the factors that triggered these studies and the challenges confronting scientists and clinicians; the intellectual, institutional, and social factors that guided the work; the crucial insights; and the vistas that the prevention of Rh disease has opened in fetal medicine. Participants include Professor Robin Coombs, the late Professor Ronald Finn, Dr Nevin Hughes-Jones, Professor Patrick Mollison, Dr Archie Norman, Dr Derrick Tovey, Professor Charles Whitfield, Professor John Woodrow and Professor Doris Zallen.